As stated above, the cleaning is the hardest part. If your 13 y/o is capable and WILLING to clean their cage several times each day, then they make a fun pet. However, if you go even ONE day without cleaning the cage.....whoa! Watch out!
I had MANY ferrets at one time. We had adopted 8 of the little furry rascals from a local ferret rescue. They are histarical to watch! They bounce and play and roll around like kittens and puppies. They nibble human toes (which you should discourage because once they get bigger it HURTS!) and chase you (or other ferrets, your dog, or anything else that moves!) and make cute little happy noises. They enjoy a good snuggle and (once they are OLDER) will curl up in your lap and nap.
However, keeping ferrets is racked with heartache. They are so overbred that cancers and other problems are the NORM not the unusual.
Most, often end up with one form or another by the age of 2 or 3, and pass on well before they should. You become SO attached to them (they're like little dogs...) that their death will crush you. We burried 6 of our eight over the 4 years we owned them and finally rehomed the last 2 because we couldn't bare the loss anymore, and just couldn't think about those 2 passing. We never got anymore either, and though I think they are adorable, I would never own another. Its just too sad for me.
My kids are 8 and 7 and they LOVED the ferrets and running up and down the halls with them, and hearing their silly little "he he he he" noises they make when happy. I have thousands of photos that we cant bare to look at anymore. When our personal 'fave' of the 8 passed after we spent hundreds of dollars trying to save.....that was it for us. Our hearts were broken real good.
Ferrets are rather expensive to keep, when done correctly. They need a large cage, and top of the line foods, toys, and they need to see a vet twice as often as a puppy does. When (if) they get sick, many vets are inexperienced in treating them, so proper vet care might be a problem. Even if your vet can treat them, it will cost you top dollar. They need to be vaccinated like puppies, and if you 'miss' a dose, you have to start all over again. Some cities and states dont allow them, so you'll have to check on that as well.
Bottom line, they are adorable and fun. But, you as the parent will end up responsible for most of the cleaning up (we all know how it goes with kids and pets!), the feeding, and the vet bills. But it will be your daughter who will feel the pain most when they pass after the short lives comparable to that of a hamster.
If you are game for all that and more that comes with keeping ferrets, then go for it. If not, maybe she would consider another type of pet that doesnt require quite so much care? Hedgehogs are cute and fun, and MUCH easier to care for.
